The present invention relates to a helical-scan-type magnetic tape recording and/or reproducing apparatus. More specifically, the invention relates to a magnetic tape recording and/or reproducing apparatus which can function as a video tape recorder or as an audio tape recorder utilizing a common magnetic tape. Still more particularly, the invention relates to a multi-channel magnetic tape recording and/or reproducing apparatus with an indicator for the recorded channel.
U.S. Pat. No. 4,542,419, issued to Minoru MORIO et al., on Sep. 17, 1985 discloses a helical-scan magnetic tape recording and/or reproducing apparatus which can operate either as a video tape recorder or as an audio tape recorder, such as a pulse-code-modulated (PCM) audio signal recorder. In this type of recording and/or reproducing apparatus, a magnetic tape is wrapped around a rotary head drum at an angle relative to the magnetic head path so as to define video and audio recording areas on the tape. In a normal video recording mode, the recording and/or reproducing apparatus records or reproduces a PCM audio signal on the audio recording area, in which the PCM audio signal is to be recorded by time-base compression. On the other hand, in an audio recording mode, the recording and/or reproducing apparatus uses not only the audio recording area but also the video recording area for PCM audio signal recording. In the latter case, the video recording area is divided into a plurality of segments, each of which corresponds to the audio recording area and records time-base-compressed PCM audio signals in substantially the same format as is recorded in the audio recording area.
With this arrangement, a plurality of PCM audio signal recording channels are formed on the magnetic tape. In the normal VTR tape recorder, each recording track is divided into the video recording area and the audio recording area respectively covering 180.degree. and 36.degree. of rotary head drum rotation. When the recording and/or reproducing apparatus is operating in a PCM audio recording mode, the video recording area is divided into 5 segments, each corresponding to 36.degree. of rotary head drum rotation. The segments on the track form a sequence of channels for PCM audio recording. Therefore, in the aforementioned example, 6 channels are formed on the magnetic tape. Normally, a single channel is used for one cycle of PCM audio signal recording. Therefore, 6 cycles of PCM audio recording can be performed on a single magnetic tape.
On tapes on which some PCM audio recording has been performed, the channel available for the next audio recording, i.e., a blank channel, must be selected for a next cycle of PCM audio recording by the recording and/or reproducing apparatus. On the other hand, when the recorded PCM audio signal is to be reproduced, the channel corresponding to the desired program must be selected.
A difficulty is encountered in prior proposed systems in selecting the channel for the next cycle of audio signal recording, since there is no way to distinguish between pre-recorded channels and unused channels except by reproducing each channel. This is not at all convenient for utilizing the recording and/or reproducing apparatus in an audio recording mode.